Influence of the nature of hydrogen halides and metal cations on the interaction types between borazine and hydrogen halides.

The interactions between the H atom of borazine and hydrogen halide (HX, X = F, Cl, Br, and I) have been studied systematically. Four structures (a, b, c, and d) have been observed. The cyclic structure a is combined through a NH···X hydrogen bond and a BH···HX dihydrogen bond, a NH···X hydrogen bond and a BH···X halogen-hydride interaction are responsible for the cyclic structure b, structures c and d are maintained by a dihydrogen bond and a halogen-hydride interaction, respectively. Structures a and b are stable in energy, while structures c and d are unstable in energy. Structures a and b can transform each other through structure c or d. The interaction mode and strength are related to the nature of HX. The cation-π interaction of borazine with Li(+) and Mg(2+) causes a change in the interaction mode in structures a and b, and has an enhancing effect on the interaction strength in a and b.